Work will be continued on the regulation of hepatic ketogenesis. Emphasis will be placed on the mechanism activating carnitine acyltransferases I and II, which appear to be the rate controlling enzymes for fatty acid oxidation and ketogenesis. Interrelationships between carnitine and coenzyme A will be investigated in this regard. The aim will be to determine how fasting and diabetes cause accelerated hepatic ketogenesis. BIBLIOGRAPHIC REFERENCES: McGarry, J.D. and D.W. Foster. An improved and simplified radiosotopic assay for the determination of free and esterified carnitine. J. Lipid Res. 17:277, 1976. Robles-Valdes, C., J.D. McGarry and D.W. Foster. Maternal fetal carnitine relationships and neonatal ketosis in the rat. J. Biol. Chem. 251:6007, 1976.